98 
BULLETIN OF THE LABORATORIES 
iy been referred to Holopea, both by collectors and writers on geology. 
They consist for the most part of the upper three, or three and a half 
volutions of a shell which seems identical with the form just described. 
The character of the volutions and surface striations are the same; the 
last volution is also expanded at the aperture, giving greater distinct- 
ness to the lip, and having the same straightening effect on the curva- 
ture of the shell at this point. 
In the New Carlisle specimens, however, the upper side of the last 
third of the last volution is flattened above and quite evenly rounded 
on the sides, forming in this way a line of elevation along the upper 
side of the volution, where the gradual curvature of the sides meets 
the flattened portion above. In the Soldiers’ Home specimen which 
is best preserved, there is no flattening along the upper plane of this 
last volution, but instead, there is an even curvature from the suture 
to the lower side, an elevation being thus formed at the umbilicus into 
which the side of the lower third of the volution bends abruptly. 
The aperture of this specimen, therefore, is oblique to a ver- 
tical diameter of the shell, whereas, in the New Carlisle speci- 
mens the aperture seems to have its gieatest diameter vertical 
to the shell. Other forms, however, occur at the Soldiers’ Home, 
among which are some with deep sutures and less oblique apertures ; 
some quite similar to the New Carlisle specimens, but much smaller; 
a specimen with its coils arranged somewhat like P. plebium, but only 
half its size ( Fig. 3 b. ); and a specimen varying to the opposite ex- 
treme, with the last volution extremely ventricose, the upper vo- 
lution only moderately raised, the part towards the aperture, however, 
being lacking (Fig. 3a). All the forms from the Soldiers’ Home 
differ from the New Carlisle specimens, however, in their smaller size, 
the New Carlisle specimens differing in turn from the typical western 
forms chiefly in their smaller size. All these Clinton forms differ 
from the western in the slight expansion of the lip at the aperture and 
the straightened appearance of the volutions at this point, the rate of 
curvature decreasing. 
Specimens last described, at Soldiers’ Home Quarries, Clinton 
Group. 
(The variations here indicated will be carefully hgured in the next 
paper. ) 
